Dynamo-electric machine.



B. C. LAMME.

DYNAMO ELECTRIC MACHINE. APPLICATION FILED Aue.22. 191.3.

1,244,509. Patented Oct. 30,1917.

TNESSES: I INVENTOR Ki -QM UNITEDrSTATES PATENT OFFICEf BENJAMIN G. LAMME, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB T6 WEST II TGH OITSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

DYNAMO-ELECTBIG MAUREE- Specification of Letters Patent.

Patented Oct. 30, 191 '1.

means for reducing the circulation of eddycurrents in the laminations caused by fringing of the magnetic flux in the annular ventilating spaces.

Another object of my invention is to provide a simple and inexpensive construction embodying the above means that may be readily applied to dynamo-electric machines of the above-indicated type.

In the construction of dynamo-electric machines of large capacity and employing axial ventilation, it'has been found necessaryto provide annular vent-spaces in the armature cores in order to allow the air to escape from the axial ducts and from the air gap. However, considerable trouble has been experienced from over-heatin of the f portions of the core adjacent to t e ventspaces due to the fact that the magnetic flux from the field poles can pass upwardly into and enter the sides of the vent-s ace in a direction substantially perpendicu ar to the face of the laminations thus inducing eddy currents therein and resulting in objectionable heating. Obviously, the wider the ventspace the more tendency there is for large flux in the sides of the laminations and since 40 a relatively wide opening is required at the ortion of the core remote from the air gap in order to allow the ventilating air to escape, various schemes have been proposed to limit the circulation of excessive eddy currents in the laminations adjacent to the vent-spaces.

According to my invention, I provide a laminated core having an annular ventspace, the laminations on the sides of which positely-disposed at equal angles to the axis of the machine. In this way, an annular vent-space substantially trapezoidal in section, is formed, the smaller opening being 5 in the periphery adjacent to the air-gap of converge radially inwardly, thus being opthe machine. Consequently, the number of lines of force entering the annular ventspace will be limited by the size of the opening adjacent to the air gap while an opening several times the size of the former may be employed at the back ofthe stator without increasing the heating due to eddy currents.

In the accompanying drawing, the single figure is a view in longitudinal section of a portion of a dynamo-electric machine constructed in accordance with my invention.

Referring to the drawing, the illustrated portion of a dynamo-electric machine comprises a rotor 1 of any well-known type and a stator 1" that embodies a frame 2 of any suitable form, end-plates 3 and a core 4 that is suitably clamped between the end-plates.

The core 4. preferably comprises a plurality of groups of laminations of the usual or any desired material and thickness that are oppositely-disposed at equal angles to the axis of the machine on the sides of a central vent-space 5, thereby giving the ventspace the form of a ring substantially trapezoidal in form, and with the smaller opening in the periphery adjacent to the air gap between the rotor and the stator. From the foregoing construction, it will be seen that the groups of laminations on the sides of the vent-space, when viewed therefrom, severally present the form of a frustum of a cone superposed on a cylinder. A plurality ofwedge-shaped spacing fingers 6 of any convenient type are suitably secured to the core on the sides of the vent-space 5, or any other suitable means of spacing'and supporting the angularly-disposed laminations may be employed. Longitudinal vent-spaces 7 t at communicate with the annular ventspace 5 may or may not be utilized. The end-plates 3 may be of any form that is adapted to rigidly engage the laminations of the core 4 at the ends thereof. As shown, the end-plates have a frusto-conical inner surface similar to the frusto-conical sides of the vent-space 5.

Although, for illustrative purposes, I have shown and described my invention as embodied in a particular structure, I wish it to be understood that I do not limit the invention to the specific details herein set forth. I, therefore, desire that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A dynamo-electric machine comprising relatively movable members separated by an air gap, one of said members having an annular vent-space of smaller width at the periphery adjacent to said air gap than at other portions thereof.

2. A dynamo-electric machine comprising relatively movable magnetizable members separated by an air gap, one of said members having an annular vent-space radially diflerent portions of which are of difierent widths, the smallest width being at that portion adjacent to the said air gap.

3. In a dynamo-electric machine, a magnetizable member provided with an annular vent-space substantially trapezoidal in cross section, the said vent-space being narrowest at its inner periphery. I

4:. In a dynamo-electric machine, a magnetizable member provided with an annular vent-space having faces oppositely disposed at acute angles to the axis of said magnetizable member, the said faces being nearest to each other at the inner periphery of said vent-space.

5. A dynamo-electric machine comprising relatively movable members one of which embodies a plurality of groups of magnetizable laminations oppositely disposed at equal acute angles to the axis of the ma chine, the said groups being nearer to each other at the inner periphery of said ventspace than at other portions thereof.

6. A dynamo-electric machine comprising relatively movable members separated by an air gap one of which embodies a plurality of magnetizable laminations and has an annular vent-space, the laminations on the sides of which are oppositely-disposed at equal acute angles to the axis of the machine and are nearest to each other at that portion of the vent-space adjacent to said air gap.

7. A dynamo-electric machine comprising relatively movable members, one of which embodies a plurality of magnetizable laminations and has an annular vent-space, the laminations on the sides of which are oppositely-disposed at acute angles to the axis of the machine and are nearest to each other at the inner periphery of said vent-space.

8. In a dynamo-electric machine, a magnetizable member provided with an annular vent-space, the sections onthe sides of which constitute oppositely-inclined groups of laminations severally having a frusto conical form, the said sections being nearest to each other at the inner periphery of said vent-space. I

9. In a dynamo-electric machine, a magnetizable member rovided with an annular vent-space the sectlons on the sides of which constitute oppositely-disposed groups of laminations severally having a frusto: conical form, and further comprisin a plurality of trapezoidal spacing members interposed between the said groups of laminations, the said vent-space being narrowest at its inner periphery. I

In testimony whereof, I have hereunto subscribed my name this 14th day of August 1913.

BENJ. G. LAMME.

Witnesses:

F. T. HAGUE, B. B. HINES. 

